Add a factory and defines for native Linux surfaces.

ui/gfx/native_widget_types.h

Index: ui/gfx/native_widget_types.h
diff --git a/ui/gfx/native_widget_types.h b/ui/gfx/native_widget_types.h
index 720e347bd35c291a31ece1a481cc7a3bf5acb2aa..b0f72d0cdd768047f5fb31a8dac28c15980e999f 100644
--- a/ui/gfx/native_widget_types.h
+++ b/ui/gfx/native_widget_types.h
@@ -250,6 +250,9 @@ static inline NativeView NativeViewFromIdInBrowser(NativeViewId id) {
 #elif defined(OS_ANDROID)
   typedef uint64 PluginWindowHandle;
   const PluginWindowHandle kNullPluginWindow = 0;
+#elif defined(USE_NATIVE_SURFACE_LINUX)
+  typedef intptr_t PluginWindowHandle;
+  const PluginWindowHandle kNullPluginWindow = 0;
 #else
   // On OS X we don't have windowed plugins.
   // We use a NULL/0 PluginWindowHandle in shared code to indicate there
@@ -315,6 +318,9 @@ const AcceleratedWidget kNullAcceleratedWidget = 0;
 #elif defined(OS_ANDROID)
 typedef ANativeWindow* AcceleratedWidget;
 const AcceleratedWidget kNullAcceleratedWidget = 0;
+#elif defined(USE_NATIVE_SURFACE_LINUX)
+typedef intptr_t AcceleratedWidget;
+const AcceleratedWidget kNullAcceleratedWidget = 0;
 #else
 #error unknown platform
 #endif